Question

 Two balls are drawn from an urn containing 3 white, 5 red and 2 black balls, one by one without replacement. What is the probability that at least one ball is red?

Answer 1

 P(atleast one ball is Red) 
`= 1 - P (No ball is red)`

`= 1-P (Non  red)xx  p(No Red  II)`

`= 1 - 5/10xx 4/9 = 1- = 20/90 = 7/9`